In United Kingdom Patent Application No. GB 2255257 is described an earlier concept for an Asynchronous Transfer Mode (ATM) self-routing network which may be used for Private Networks, Virtual Private Networks and distributed Local Area Switches in the Public Network. The service is connectionless using a, special format of the address octets i n the cell header; cells are directed to their respective destinations by an Interpreter held in each elemental switch or at each switch input port, depending upon implementation. No overhead is required in the cell Information Field which therefore corresponds to the payload in the ATM layer or a composite network; hence the use of standard adaption-layer formats is not compromised. This application is included herein by reference.
The network is divided into Mini-Networks typically with up to 256 user Network Ports. The size of the address field limits the number of Mini-Networks served to 16. The resultant cell header format is shown in FIG. 1.
It will be seen that such a network is limited to a maximum of 4k (4,096) User Network Ports, although thee use of multiplexers can substantially increase this number.